PhysicalLightingModel.js 3.4 KB

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  1. import BRDF_Lambert from './BSDF/BRDF_Lambert.js';
  2. import BRDF_GGX from './BSDF/BRDF_GGX.js';
  3. import DFGApprox from './BSDF/DFGApprox.js';
  4. import { lightingModel } from '../core/LightingModel.js';
  5. import { temp } from '../core/VarNode.js';
  6. import { diffuseColor, specularColor, roughness } from '../core/PropertyNode.js';
  7. import { transformedNormalView } from '../accessors/NormalNode.js';
  8. import { positionViewDirection } from '../accessors/PositionNode.js';
  9. import { ShaderNode, float, vec3 } from '../shadernode/ShaderNode.js';
  10. // Fdez-Agüera's "Multiple-Scattering Microfacet Model for Real-Time Image Based Lighting"
  11. // Approximates multiscattering in order to preserve energy.
  12. // http://www.jcgt.org/published/0008/01/03/
  13. const computeMultiscattering = ( singleScatter, multiScatter, specularF90 = float( 1 ) ) => {
  14. const fab = DFGApprox.call( { roughness } );
  15. const FssEss = specularColor.mul( fab.x ).add( specularF90.mul( fab.y ) );
  16. const Ess = fab.x.add( fab.y );
  17. const Ems = Ess.oneMinus();
  18. const Favg = specularColor.add( specularColor.oneMinus().mul( 0.047619 ) ); // 1/21
  19. const Fms = FssEss.mul( Favg ).div( Ems.mul( Favg ).oneMinus() );
  20. singleScatter.addAssign( FssEss );
  21. multiScatter.addAssign( Fms.mul( Ems ) );
  22. };
  23. const RE_IndirectSpecular_Physical = new ShaderNode( ( inputs ) => {
  24. const { radiance, iblIrradiance, reflectedLight } = inputs;
  25. // Both indirect specular and indirect diffuse light accumulate here
  26. const singleScattering = temp( vec3() );
  27. const multiScattering = temp( vec3() );
  28. const cosineWeightedIrradiance = iblIrradiance.mul( 1 / Math.PI );
  29. computeMultiscattering( singleScattering, multiScattering );
  30. const diffuse = diffuseColor.mul( singleScattering.add( multiScattering ).oneMinus() );
  31. reflectedLight.indirectSpecular.addAssign( radiance.mul( singleScattering ) );
  32. reflectedLight.indirectSpecular.addAssign( multiScattering.mul( cosineWeightedIrradiance ) );
  33. reflectedLight.indirectDiffuse.addAssign( diffuse.mul( cosineWeightedIrradiance ) );
  34. } );
  35. const RE_IndirectDiffuse_Physical = new ShaderNode( ( inputs ) => {
  36. const { irradiance, reflectedLight } = inputs;
  37. reflectedLight.indirectDiffuse.addAssign( irradiance.mul( BRDF_Lambert.call( { diffuseColor } ) ) );
  38. } );
  39. const RE_Direct_Physical = new ShaderNode( ( inputs ) => {
  40. const { lightDirection, lightColor, reflectedLight } = inputs;
  41. const dotNL = transformedNormalView.dot( lightDirection ).clamp();
  42. const irradiance = dotNL.mul( lightColor );
  43. reflectedLight.directDiffuse.addAssign( irradiance.mul( BRDF_Lambert.call( { diffuseColor: diffuseColor.rgb } ) ) );
  44. reflectedLight.directSpecular.addAssign( irradiance.mul( BRDF_GGX.call( { lightDirection, f0: specularColor, f90: 1, roughness } ) ) );
  45. } );
  46. const RE_AmbientOcclusion_Physical = new ShaderNode( ( { ambientOcclusion, reflectedLight } ) => {
  47. const dotNV = transformedNormalView.dot( positionViewDirection ).clamp();
  48. const aoNV = dotNV.add( ambientOcclusion );
  49. const aoExp = roughness.mul( - 16.0 ).oneMinus().negate().exp2();
  50. const aoNode = ambientOcclusion.sub( aoNV.pow( aoExp ).oneMinus() ).clamp();
  51. reflectedLight.indirectDiffuse.mulAssign( ambientOcclusion );
  52. reflectedLight.indirectSpecular.mulAssign( aoNode );
  53. } );
  54. const physicalLightingModel = lightingModel( RE_Direct_Physical, RE_IndirectDiffuse_Physical, RE_IndirectSpecular_Physical, RE_AmbientOcclusion_Physical );
  55. export default physicalLightingModel;